ACL Reconstruction: The Operation

The ‘keyhole surgery’ operation to reconstruct the ACL involves replacing it with other strong tendons from areas around the knee. Two main grafts are in common use: the Hamstring Tendon graft and the Patella Tendon graft. Both are considered to be equally good and the choice usually depends on the surgeon’s preference. Currently the Hamstring Tendon graft is favoured in most patients and it is probably best to avoid using the patella tendon if there is significant pre-existing pain in the front of the knee, or where employment involves kneeling or squatting. Postoperative rehabilitation is the same for each graft. The hamstring graft is made from the semi-tendonosis and gracilis tendons, which are cord like structures behind the inner aspect of the knee. These two tendons are taken through a small incision on the front of the tibia and are folded in to make four, five or six stranded structure

The patella tendon graft is made from the central strip of the patella tendon that runs from the knee cap (patella) to the tibia; a small piece of bone is kept attached to the ligament at each end .

Bone graft from the tibia is inserted at the end of the operation into the kneecap to restore contour and to help with kneeling.

Surgery is performed under general anaesthesia and usually takes 1–1/2 hours. The chosen graft is harvested through small incisions and is prepared into a new ligament. The main part of the procedure is performed via keyhole surgery (arthroscopy). The bulk of the old ACL is removed to allow space for the new graft.

The inside of the knee is prepared and tunnels are made in the tibia and femur at the anatomical site of the attachment points of the old ligament. The new Hamstring Graft ligament is then held in place within the tunnels using a small metal bar (endobutton) on the femur and an absorbable screw at the shin bone end. A Patella Tendon graft is held in place by two bio-absorbable screws which are slowly incorporated by the body.

These fixation devices do not usually need to be removed.

If the meniscus is torn, or the articular cartilage is damaged, then such damage can be tidied up or repaired during the same procedure. This may affect the rehabilitation time scales post operatively.